Automatic transmissions for the transmittal of power from a power source to a load are well known and some have employed planetary gearsets. However, such transmissions have been limited with respect to the range of gear ratios attainable thereby, resulting in less than optimum system economy and performance.
A search has been conducted in the U.S. Patent and Trademark Office with respect to the subject matter of this invention and the following U.S. Pat. Nos. relating to automatic power transmissions have been noted in that search as the closest prior art:
______________________________________ 2,523,619 4,472,984 3,209,620 4,579,019 3,893,352 4,598,610 4,327,604 4,625,588 4,334,440 ______________________________________
U.S. Pat. No. 2,523,619 discloses a conventional type of automatic transmission having a torque converter and planetary gear components, in which sliding mechanical clutches are employed rather than the more normal hydraulic disc clutches. The transmission has only a limited number of gear ratios.
U.S. Pat. No. 3,209,620 also discloses a conventional type of automatic transmission having planetary gear components, in which the torque converter is replaced by a magnetic particle clutch. Again, the transmission has only a limited number of gear ratios.
U.S. Pat. No. 3,893,352 discloses an automatic transmission design having a variable gear ratio design utilizing planetary gear sets and a hydraulic screw pump which controls the speed of rotation of a third member of the first planetary gearset.
U.S. Pat. No. 4,327,604 also discloses a variable ratio design of automatic transmission using planetary gearsets. In this case, one planetary gearset divides the input shaft torque and speed between two driven members of the planetary gearset.
U.S. Pat. No. 4,339,440 discloses a completely mechanical variable ratio power transmission design wherein members of three planetary gearsets are interconnected.
U.S. Pat. No. 4,472,984 discloses an automatic transmission which employs a compound planetary gearset and a torque converter. The transmission appears to possess but a single gear ratio with speed variation occurring through the torque converter.
U.S. Pat. No. 4,579,019 is similar to U.S. Pat. No. 4,327,604 in that the power input is divided and added to components in combination to achieve the desired output variation.
U.S. Pat. No. 4,598,610 is a somewhat complex variable ratio transmission using trains with gearsets linked up rather than single gearsets.
U.S. Pat. No. 4,625,588 also discloses a variable ratio transmission using planetary gearsets. Each of the planet gears of the first planetary group interact with the control sun and driven sun to permit the reaction forces in all the components to react or rotate simultaneously.